The primary objective is the development of computer-aided molecular design for both receptors of know three-dimensional structure and those of unknown structure. One aspect is development of a set of constrained amino acids (chimeric amino acids) and dipeptides which restrict the conformational freedom while still retaining necessary sidechain functionality for recognition. These are incorporated into biologically active peptides such as bradykinin and angiotensin to probe the receptor. Compounds are designed with specific conformational constraints and then general synthetic routes developed to prepare and incorporate them into the desired peptide sequence. Mass spectrometry is used for material characterization.